That was an extraordinary atonement on this page last Saturday. There, in an editorial ("The Peace Groups," Oct. 9), was a straightforward apology for an earlier editorial statement ("Hot Words for the Freeze," Oct. 6) that the Women's International League for Peace and Freedom is a "Soviet front" and for an implication that Women Strike for Peace is a "Soviet stooge group." Additionally, some 40 inches of space was given to statements of protest from the two organizations and from the American Civil Liberties Union. By any journalistic standard, it was a class act in acknowledgment of error.

The initial editorial, many observers said, had the regrettable effect of doing to the organizations what it charged President Reagan with doing to the nuclear freeze movement and Sen. Jeremiah Denton, with his reckless remarks, to Peace Links, sponsors of "Peaceday 1982": it smeared them. It failed to make the important distinction that appeared in Saturday's editorial: participation by the American Section of WILPF and by WSP in international forums, where communist activists steer the agenda, cannot be ruled guilt-by-association.

The first editorial lost its bearings by relying too literally on a State Department report that, among other things, attempts to keep book on "front groups." The report footnotes a reference to WILPF and to Women's International Democratic Federation, the reputed connection for WSP. Saturday's editorial noted that State has designated WILPF as "communist affiliated" for purposes of issuing visas, but adds that that nomenclature has nothing to do with the group's American Section.

Both Meg Greenfield and Stephen Rosenfeld, editor and deputy editor respectively of the editorial page, acknowledge "tripping over names and institutional associations . . . that drew us to faulty conclusions. . . . We went back over it all, decided what was the thing to do . . . and corrected it as soon as we could . . . ." With regard to Mr. Reagan and Sen. Denton, Miss Greenfield says, "We were distinguishing ourselves from them. Our position was never theirs. We were obviously concerned about putting groups where they didn't belong."

The axis here is the national concern about nuclear weapons, and the debate is running loose. You have the president accused by certain proponents of engaging in "McCarthy-style smear tactics." Colleagues are shouting "bully" and "shame" at Sen. Denton. Were the arguments propelled as much by logic as by emotion, and were the story covered more thoroughly by the press, fewer unnecessary offenses would be committed and a wider audience would be better informed.

Impassioned things are said and written from pretty thin stuff. Sen. Denton, who was dead wrong when he implied that Peace Links was pregnant with subversion, backed away from that in a subsequent radio interview. Near as I can tell, that has been ignored by newspapers, including The Post, which carried his initial remarks. That story, as his office argues, failed to note that he was opposed to a Senate resolution to proclaim Oct. 10 "National Peace Day." Right or wrong, he read the resolution introduced by Sen. Dale Bumpers, whose wife is a founding organizer of Peace Links, as promoting a nuclear freeze. That, Sen. Denton maintains, would have the president contradicting his own policies. It is at least fair to expect that to be a part of the story. The Post has also neglected to report that in a meeting with reporters at the National Press Club, Mrs. Bumpers criticized the editorial page.

News coverage of the freeze debate should reach beyond the low denominator that assures space if you impugn another's motives. The notion that the movement is a morality play written and directed by alien communists to be acted only by American citizens is buncombe, and the press knows it. The main point of The Post's first editorial --that genuine civil debate is abused if patriotism is questioned or official policy misrepresented--is unassailable. Interested people want a clearer view of where the substantive differences are on how we get from here to acceptable weapons control. They've had enough hot air.